Experimental Study On Steel And Steel Fiber Reinforced High-strength Concrete Under Eccentric Compression

With the development of super high-rise and long-span buildings,new composite columns with high bearing capacity are increasingly needed.Steel reinforced high-strength concrete(SHSC)column is one of them,but it has the disadvantage of high brittleness.Steel fiber is now added to improve the disadvantage of steel reinforced high-strength concrete column.Finally combined with the advantages of their respective materials,steel and steel fiber reinforced high-strength concrete(SSFRHSC)column was proposed.In engineering,most of the columns are under eccentric compression,so it is necessary to study the mechanical properties of SSFRHSC columns under eccentric compression.In this paper,the SSFRHSC column was subjected to static load test research,and six test pieces were designed and manufactured.The bearing capacity of the SSFRHSC column at different eccentricity of 0mm,40mm,80mm,and 120mm,and different steel fiber volume ratios of 0%,0.5%,and 1.0%was studied.Force and failure characteristics and crack characteristics.Obtained the load-displacement curve of the column,and controlled cross-sectional strain and crack development data under different loads,analyzed the influence of different steel fiber volume ratios and changes in eccentricity on the mechanical properties of the SSFRHSC column,including SSFRHSC Column’s failure morphology and stress mechanism.The results showed that:(1)The SSFRHSC column has strong bearing capacity,stiffness and good ductility,and the type of failure can be divided into two types of tensile failure and compressive failure according to different eccentric distances,and the type of eccentric compression failure of the ordinary SRC column size similar;(2)The bearing capacity of the SSFRHSC biased column is related to the steel fiber volume ratio and eccentricity.The steel fiber volume ratio is from 0%to 1%,and each increase of 0.5%increases the ultimate bearing capacity of the combined column by 9.47%and 9.79%,respectively;When the eccentricity increases from 0mm to 120mm by 40mm,the peak load is reduced by 39.80%,38.69%and 32.70%,respectively.SSFRHSC column has strong deformability and performance,steel fiber has a good inhibition effect on brittle cracking of high-strength concrete,and the volume rate of steel fiber is from 0%to 1%,each increase of 0.5%,SSFRHSC column cracking load is respectively Increase by 27.50%and 13.73%;(3)The addition of steel fibers significantly improves the ductility of SSFRHSC eccentric compression columns,and the volume ratio of steel fibers from 0%to 1%,with each increase of 0.5%,the ductility coefficient increases by 22.94%and 9.33%,respectively.The eccentricity also has a great influence on the ductility coefficient.For each eccentricity from 40mm to 120mm,the SSFRHSC column ductility coefficient increases by 20.77%and 17.78%for each additional 40mm.(4)Finally,based on simplified calculation method,improved "Technical Specification for Steel Reinforced Concrete Structure" and improved "Code for Design of Combined Structure",and calculation method of full-section stress calculation,the calculation result is close to the test value.The applicability of the crack formula of ordinary concrete structures in the calculation of SSFRHSC structural cracks is calculated and analyzed to provide reference value in actual engineering calculations.